Issue #1677 - Part 1: Import new V8 regexp code with Mozilla's header modifications

1 files changed, 140 insertions, 0 deletions

diff --git a/js/src/regexp/regexp-stack.h b/js/src/regexp/regexp-stack.h
new file mode 100644
index 000000000..2c2cf2630
--- /dev/null
+++ b/js/src/regexp/regexp-stack.h
@@ -0,0 +1,140 @@
+// Copyright 2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_STACK_H_
+#define V8_REGEXP_REGEXP_STACK_H_
+
+
+namespace v8 {
+namespace internal {
+
+class RegExpStack;
+
+// Maintains a per-v8thread stack area that can be used by irregexp
+// implementation for its backtracking stack.
+// Since there is only one stack area, the Irregexp implementation is not
+// re-entrant. I.e., no regular expressions may be executed in the same thread
+// during a preempted Irregexp execution.
+class RegExpStackScope {
+ public:
+  // Create and delete an instance to control the life-time of a growing stack.
+
+  // Initializes the stack memory area if necessary.
+  explicit RegExpStackScope(Isolate* isolate);
+  ~RegExpStackScope();  // Releases the stack if it has grown.
+
+  RegExpStack* stack() const { return regexp_stack_; }
+
+ private:
+  RegExpStack* regexp_stack_;
+
+  DISALLOW_COPY_AND_ASSIGN(RegExpStackScope);
+};
+
+
+class RegExpStack {
+ public:
+  // Number of allocated locations on the stack below the limit.
+  // No sequence of pushes must be longer that this without doing a stack-limit
+  // check.
+  static constexpr int kStackLimitSlack = 32;
+
+  // Gives the top of the memory used as stack.
+  Address stack_base() {
+    DCHECK_NE(0, thread_local_.memory_size_);
+    DCHECK_EQ(thread_local_.memory_top_,
+              thread_local_.memory_ + thread_local_.memory_size_);
+    return reinterpret_cast<Address>(thread_local_.memory_top_);
+  }
+
+  // The total size of the memory allocated for the stack.
+  size_t stack_capacity() { return thread_local_.memory_size_; }
+
+  // If the stack pointer gets below the limit, we should react and
+  // either grow the stack or report an out-of-stack exception.
+  // There is only a limited number of locations below the stack limit,
+  // so users of the stack should check the stack limit during any
+  // sequence of pushes longer that this.
+  Address* limit_address_address() { return &(thread_local_.limit_); }
+
+  // Ensures that there is a memory area with at least the specified size.
+  // If passing zero, the default/minimum size buffer is allocated.
+  Address EnsureCapacity(size_t size);
+
+  // Thread local archiving.
+  static constexpr int ArchiveSpacePerThread() {
+    return static_cast<int>(sizeof(ThreadLocal));
+  }
+  char* ArchiveStack(char* to);
+  char* RestoreStack(char* from);
+  void FreeThreadResources() { thread_local_.ResetToStaticStack(this); }
+
+  // Maximal size of allocated stack area.
+  static constexpr size_t kMaximumStackSize = 64 * MB;
+
+ private:
+  RegExpStack();
+  ~RegExpStack();
+
+  // Artificial limit used when the thread-local state has been destroyed.
+  static const Address kMemoryTop =
+      static_cast<Address>(static_cast<uintptr_t>(-1));
+
+  // Minimal size of dynamically-allocated stack area.
+  static constexpr size_t kMinimumDynamicStackSize = 1 * KB;
+
+  // In addition to dynamically-allocated, variable-sized stacks, we also have
+  // a statically allocated and sized area that is used whenever no dynamic
+  // stack is allocated. This guarantees that a stack is always available and
+  // we can skip availability-checks later on.
+  // It's double the slack size to ensure that we have a bit of breathing room
+  // before NativeRegExpMacroAssembler::GrowStack must be called.
+  static constexpr size_t kStaticStackSize =
+      2 * kStackLimitSlack * kSystemPointerSize;
+  byte static_stack_[kStaticStackSize] = {0};
+
+  STATIC_ASSERT(kStaticStackSize <= kMaximumStackSize);
+
+  // Structure holding the allocated memory, size and limit.
+  struct ThreadLocal {
+    explicit ThreadLocal(RegExpStack* regexp_stack) {
+      ResetToStaticStack(regexp_stack);
+    }
+
+    // If memory_size_ > 0 then memory_ and memory_top_ must be non-nullptr
+    // and memory_top_ = memory_ + memory_size_
+    byte* memory_ = nullptr;
+    byte* memory_top_ = nullptr;
+    size_t memory_size_ = 0;
+    Address limit_ = kNullAddress;
+    bool owns_memory_ = false;  // Whether memory_ is owned and must be freed.
+
+    void ResetToStaticStack(RegExpStack* regexp_stack);
+    void FreeAndInvalidate();
+  };
+
+  // Address of top of memory used as stack.
+  Address memory_top_address_address() {
+    return reinterpret_cast<Address>(&thread_local_.memory_top_);
+  }
+
+  // Resets the buffer if it has grown beyond the default/minimum size.
+  // After this, the buffer is either the default size, or it is empty, so
+  // you have to call EnsureCapacity before using it again.
+  void Reset();
+
+  ThreadLocal thread_local_;
+  Isolate* isolate_;
+
+  friend class ExternalReference;
+  friend class Isolate;
+  friend class RegExpStackScope;
+
+  DISALLOW_COPY_AND_ASSIGN(RegExpStack);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_STACK_H_